Conventional vehicle support frames can be composed of different materials including, for example, steel, aluminum and reinforced polymer composites. Vehicle manufacturers attempt to strike the balance between weight reduction and structural rigidity. It is desirable to design lightweight vehicle frames for full-sized light trucks. Aluminum structural members can be designed to achieve up to 50% weight reduction while still meeting performance targets. Joining aluminum members to steel frame rails presents challenges as the two materials, when welded, have limited structural integrity.
One existing reference teaches the use of an overlapping configuration for the rails of dissimilar materials. A first and second structural member sandwiches one end of a third structural member and adhesive is applied therebetween. The second structural member is thereafter welded to the first structural member. U.S. Patent Publication No. 2009/0188206, titled “System and Method for Joining Dissimilar Materials” teaches an overlapping configuration with a surface weld on the second structural member. Still, it is desirable to improve this design by providing a point of access for spot weld fixtures or other weld fixtures that require a clamped fitting.
Another patent publication, U.S. Patent Publication No. 2006/0032895, titled “Method for Joining Axle Components” discusses joining two tubes composed of the same or dissimilar materials using magnetic forming. This process uses a forming band placed at an opposite end of an electromagnetic actuator in order to form multiple tubes; therefore, configuration options are limited for this assembly. This process is also more expensive and requires more energy than most welding and/or mechanical locking techniques.
Therefore, it is desirable to have improved interconnecting techniques for joining two structural members composed of dissimilar materials.